Dynamic Spectrum Management

1. A dynamic spectrum management (DSM) engine comprising: a transceiver configured to: transmit a first sensing task request to at least two of a plurality of wireless transmit/receive units (WTRUs) requesting that the at least two of the plurality of WTRUs measure information indicative of usage of spectrum by other devices, receive first sensing results from a first WTRU of the at least two of the plurality of WTRUs at a plurality of periodic intervals, and receive second sensing results from a second WTRU of the at least two of the plurality of WTRUs at the plurality of periodic intervals, wherein the first sensing results and the second sensing results indicate whether, at each of the plurality of periodic intervals, the spectrum is being used by the other devices at a time that the information was measured; and a processing unit configured to: determine whether the first sensing results and the second sensing results indicate that the first WTRU and the second WTRU are uncorrelated, wherein the first WTRU and the second WTRU are not simultaneously located in an interference area with respect to a third WTRU of the at least two of the plurality of WTRUs, and select a subset of the at least two of the plurality of WTRUs to which to transmit a second sensing task request based on results of the determining, wherein the subset comprises at least the first WTRU and the second WTRU, and wherein the second sensing task request instructs each WTRU of the subset to perform a second sensing task for a plurality of channels.

2. The dynamic spectrum management (DSM) engine of claim 1 , wherein: the transceiver is further configured to receive additional sensing results from each of the subset to which the second sensing task request was sent, wherein the additional sensing results comprise at least one indication that the spectrum is being used by the other devices; and the processing unit is further configured to determine whether the other devices are using the spectrum based at least on the additional sensing results and other information indicating a reliability of the additional sensing results.

3. The dynamic spectrum management (DSM) engine of claim 2 , wherein the other information comprises at least one of an estimated signal-to-noise ratio (SNR) or a number of samples used in a metric computation.

4. The dynamic spectrum management (DSM) engine of claim 2 , wherein the processing unit is further configured to determine whether the other devices are using the spectrum by: attributing a weight to each of the additional sensing results based on the other information indicating the reliability of the additional sensing results; and combining the additional sensing results into an overall metric using the weight attributed to each of the additional sensing results.

5. The dynamic spectrum management (DSM) engine of claim 1 , wherein the transceiver is further configured to transmit the second sensing task request to at least two of the subset and receive inphase/quadrature (I/Q) data samples from the at least two of the subset; and wherein the processing unit is further configured to determine whether the other devices are using the spectrum based on the received I/Q data samples.

6. The dynamic spectrum management (DSM) engine of claim 1 , wherein the third WTRU of the at least two of the plurality of WTRUs is a primary WTRU.

7. A method implemented in a dynamic spectrum management (DSM) engine, the method comprising: transmitting a first sensing task request to at least two of a plurality of wireless transmit/receive units (WTRUs) requesting that the at least two of the plurality of WTRUs measure information indicative of usage of spectrum by other devices; receiving first sensing results from a first WTRU of the at least two of the plurality of WTRUs at a plurality of periodic intervals, receiving second sensing results from a second WTRU of the at least two of the plurality of WTRUs at the plurality of periodic intervals, wherein the first sensing results and the second sensing results indicate whether, at each of the plurality of periodic intervals, the spectrum is being used by the other devices at a time that the information was measured; determining whether the first sensing results and the second sensing results indicate the first WTRU and the second WTRU are uncorrelated, wherein the first WTRU and the second WTRU are not simultaneously located in an interference area with respect to a third WTRU of the at least two of the plurality of WTRUs; and selecting a subset of the at least two of the plurality of WTRUs to which to transmit a second sensing task request based on results of the determining, wherein the subset comprises at least the first WTRU and the second WTRU, and wherein the second sensing task request instructs each WTRU of the subset to perform a second sensing task for a plurality of channels.

8. The method of claim 7 , further comprising: receiving additional sensing results from each WTRU of the subset to which the second sensing task request was sent, the additional sensing results comprising at least one indication that the spectrum is being used by the other devices; and determining whether the other devices are using the spectrum based at least on the additional sensing results and other information indicating a reliability of the additional sensing results.

9. The method of claim 8 , wherein the other information comprises at least one of an estimated signal-to-noise ratio (SNR) or a number of samples used in a metric computation.

10. The method of claim 8 , wherein the determining comprises: attributing a weight to each of the additional sensing results based on the other information; and combining the additional sensing results into an overall metric using the weight attributed to each of the additional sensing results.

11. The method of claim 7 , further comprising: transmitting the second sensing task request to at least two of the subset; receiving inphase/quadrature (I/Q) data samples from the at least two of the subset; and determining whether the other devices are using the spectrum based on the received I/Q data samples.

12. The method of claim 11 , wherein the determining whether the other devices are using the spectrum based on the received I/Q data comprises: computing an average power spectral density (PSD) based on the received I/Q data samples; and determining whether the other devices are using the spectrum based on the computed average PSD.

13. The method of claim 11 , wherein the determining whether the other devices are using the spectrum based on the received I/Q data comprises computing the average PSD over a configurable-length time window.

14. The method of claim 13 , wherein a length of the configurable-length time window depends on at least one of a type of interferer detected by the subset, an amount of time required to detect the third WTRU, a mobility of the subset, or a knowledge of a noise level on a channel.

15. The method of claim 11 , wherein the determining whether the other devices are using the spectrum based on the received I/Q data samples comprises: estimating autocorrelation properties of the received I/Q data samples; calculating a decision metric based on the estimated autocorrelation properties; determining whether the decision metric exceeds a decision threshold; on a condition that the decision metric exceeds the decision threshold, determining that the other devices are using the spectrum; and on a condition that the decision metric does not exceed the decision threshold, determining that the other devices are not using the spectrum.

16. The method of claim 15 , wherein the calculating the decision metric is performed based on: P 1 = M · R yy ⁡ ( 0 ) , P 2 = M · ∑ i = 0 M - 1 ⁢ ⁢  R yy ⁡ ( j )  2 , and ⁢ wherein the determining whether the decision metric exceeds the decision threshold is based on: P 1 2 MP 2 ⁢ ≥ < ⁢ γ , wherein y(n) is an input signal, M is a number of offset autocorrelations being considered and γ is the decision threshold, and wherein R yy is an autocorrelation.

17. The method of claim 7 , further comprising transmitting at least one new spectrum allocation to the at least two of the plurality of WTRUs on a condition that the other devices are using the spectrum that was previously allocated to the at least two of the plurality of WTRUs.

18. The method of claim 7 , further comprising generating sensing objects comprising additional information for configuring hardware of the DSM engine to obtain the first sensing results and the second sensing results, wherein the hardware is configured differently depending on a content of the additional information comprised in each respective sensing object.

19. The method of claim 7 , further comprising: allocating spectrum for use by the plurality of WTRUs; and receiving a notification from one of the plurality of WTRUs indicating that the one of the plurality of WTRUs detected a change in performance of a wireless link corresponding to use of the spectrum by the third WTRU.

20. The method of claim 7 , wherein the third WTRU of the at least two of the plurality of WTRUs is a primary WTRU.